gdbstub: move to a separate component, support multiple targets

components/esp_gdbstub/src/packet.c

@@ -0,0 +1,177 @@
+// Copyright 2015-2019 Espressif Systems (Shanghai) PTE LTD
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#include "esp_gdbstub_common.h"
+
+// GDB command input buffer
+static unsigned char s_cmd[GDBSTUB_CMD_BUFLEN];
+
+// Running checksum of the output packet
+static char s_chsum;
+
+// Send the start of a packet; reset checksum calculation.
+void esp_gdbstub_send_start()
+{
+    s_chsum = 0;
+    esp_gdbstub_putchar('$');
+}
+
+// Send a char as part of a packet
+void esp_gdbstub_send_char(char c)
+{
+    if (c == '#' || c == '$' || c == '}' || c == '*') {
+        esp_gdbstub_putchar('}');
+        esp_gdbstub_putchar(c ^ 0x20);
+        s_chsum += (c ^ 0x20) + '}';
+    } else {
+        esp_gdbstub_putchar(c);
+        s_chsum += c;
+    }
+}
+
+// Send a string as part of a packet
+void esp_gdbstub_send_str(const char *c)
+{
+    while (*c != 0) {
+        esp_gdbstub_send_char(*c);
+        c++;
+    }
+}
+
+// Send a hex val as part of a packet.
+// 'bits'/4 dictates the number of hex chars sent.
+void esp_gdbstub_send_hex(int val, int bits)
+{
+    const char* hex_chars = "0123456789abcdef";
+    for (int i = bits; i > 0; i -= 4) {
+        esp_gdbstub_send_char(hex_chars[(val >> (i - 4)) & 0xf]);
+    }
+}
+
+// Finish sending a packet.
+void esp_gdbstub_send_end()
+{
+    esp_gdbstub_putchar('#');
+    esp_gdbstub_send_hex(s_chsum, 8);
+}
+
+// Send a packet with a string as content
+void esp_gdbstub_send_str_packet(const char* str)
+{
+    esp_gdbstub_send_start();
+    if (str != NULL) {
+        esp_gdbstub_send_str(str);
+    }
+    esp_gdbstub_send_end();
+}
+
+// Grab a hex value from the gdb packet. Ptr will get positioned on the end
+// of the hex string, as far as the routine has read into it. Bits/4 indicates
+// the max amount of hex chars it gobbles up. Bits can be -1 to eat up as much
+// hex chars as possible.
+uint32_t esp_gdbstub_gethex(const unsigned char **ptr, int bits)
+{
+    int i;
+    int no;
+    uint32_t v = 0;
+    char c;
+    no = bits / 4;
+    if (bits == -1) {
+        no = 64;
+    }
+    for (i = 0; i < no; i++) {
+        c = **ptr;
+        (*ptr)++;
+        if (c >= '0' && c <= '9') {
+            v <<= 4;
+            v |= (c - '0');
+        } else if (c >= 'A' && c <= 'F') {
+            v <<= 4;
+            v |= (c - 'A') + 10;
+        } else if (c >= 'a' && c <= 'f') {
+            v <<= 4;
+            v |= (c - 'a') + 10;
+        } else if (c == '#') {
+            if (bits == -1) {
+                (*ptr)--;
+                return v;
+            }
+            return GDBSTUB_ST_ENDPACKET;
+        } else {
+            if (bits == -1) {
+                (*ptr)--;
+                return v;
+            }
+            return GDBSTUB_ST_ERR;
+        }
+    }
+    return v;
+}
+
+
+// Lower layer: grab a command packet and check the checksum
+// Calls gdbHandleCommand on the packet if the checksum is OK
+// Returns GDBSTUB_ST_OK on success, GDBSTUB_ST_ERR when checksum fails, a
+// character if it is received instead of the GDB packet
+// start char.
+int esp_gdbstub_read_command(unsigned char **out_cmd, size_t *out_size)
+{
+    unsigned char c;
+    unsigned char chsum = 0;
+    unsigned char sentchs[2];
+    int p = 0;
+    c = esp_gdbstub_getchar();
+    if (c != '$') {
+        return c;
+    }
+    while (1) {
+        c = esp_gdbstub_getchar();
+        if (c == '#') {
+            // end of packet, checksum follows
+            s_cmd[p] = 0;
+            break;
+        }
+        chsum += c;
+        if (c == '$') {
+            // restart packet?
+            chsum = 0;
+            p = 0;
+            continue;
+        }
+        if (c == '}') {
+            //escape the next char
+            c = esp_gdbstub_getchar();
+            chsum += c;
+            c ^= 0x20;
+        }
+        s_cmd[p++] = c;
+        if (p >= GDBSTUB_CMD_BUFLEN) {
+            return GDBSTUB_ST_ERR;
+        }
+    }
+    // A # has been received. Get and check the received chsum.
+    sentchs[0] = esp_gdbstub_getchar();
+    sentchs[1] = esp_gdbstub_getchar();
+    const unsigned char* c_ptr = &sentchs[0];
+    unsigned char rchsum = esp_gdbstub_gethex(&c_ptr, 8);
+    if (rchsum != chsum) {
+        esp_gdbstub_putchar('-');
+        return GDBSTUB_ST_ERR;
+    } else {
+        esp_gdbstub_putchar('+');
+        *out_cmd = s_cmd;
+        *out_size = p;
+        return GDBSTUB_ST_OK;
+    }
+}